Not true for all of Europe. My family’s graves are in Pamplona’s “new cementery” (c. 1898); in older ones, the graves were “for all eternity”; in some newer ones, they’re limited-time. The niches in that one are limited-time while the graves and mausoleums are perpetual (niches usually have room for one or two people, the graves are “multiple occupation” and get emptied occasionally; one of the things interrers do when they need to open one is check whether it will need to be emptied).
When the cementery was approaching its 100th anniversary, the Major (who was from out of town and apparently caught her advisors staring at the moon) proposed “reposessing” any plots that had been purchased as part of the original sale: someone pointed out that perhaps that could be done with those that didn’t have any current owners, but what about the ones “in use” for lack of a better word? Much shuffling of property records ensued, and the graves stayed “for perpetuity”, including a group which most definitely do not have individual owners but trying to repo them would have gotten the major hanged, drawn, quartered and sewn back together for an encore: a section occupied by unknown soldiers from the '36 civil war.